Radio communication is becoming increasingly widespread and used for a variety of communication purposes. As a result, the demand for radio frequency spectrum is likewise increasing. The concept of secondary-use radio systems has been proposed as a way of addressing radio spectrum demand. Secondary-use systems operate in the unused channels or spectrum portions of spectrum regions reserved for primary operators. Primary operators, or incumbents, are generally licensed to use a spectrum portion, such as a channel, and include entities such as television, commercial radio broadcasters, auxiliary broadcasting services (e.g. wireless microphones), radio-telephone operators, and land-mobile radio systems. Secondary use of spectrum is generally achieved though the use of cognitive radio techniques. While the CR concept is generally intended to enable frequency band sharing and reuse with incumbent users and/or other CR devices, the optimum use of spectrum already cleared of incumbent users is of particular interest to CR devices seeking to operate within the cleared spectrum.